1. Field
Example embodiments relate to light-emitting diodes using nano-rods. Other example embodiments relate to methods of manufacturing a light emitting diode.
2. Description of the Related Art
A light-emitting diode (LED) that uses a semiconductor has high efficiency. A LED is also an environmentally friendly source of light. Light-emitting devices are widely used in various fields (e.g., displays, optical communications, automobiles, common illuminations, etc.).
An LED technique for general illumination has been the focus of recent research due to the development of a white light LED technique. The white light LED may be produced using, for example, a blue LED or an ultraviolet-ray LED with a phosphor material. The white light LED may be produced by combining red, green, and blue LEDs.
The blue or ultraviolet-ray LED, which is a main constituent of the white light LED, may be formed mainly using a gallium nitride (GaN) compound semiconductor. The GaN compound semiconductor has a wide band gap. Thus, light almost having a wavelength region from visible light to ultraviolet rays may be obtained according to the composition of the nitride compound. Conventionally, a thin-film GaN LED may be formed by growing a GaN thin film on a sapphire (Al2O3) substrate. If the GaN compound semiconductor is grown as a thin film on a sapphire (Al2O3) substrate, the emission efficiency of light is reduced due to the mismatch of the lattice constant, or the thermal expansion coefficient, of the thin film GaN LED. Also, the manufacturing costs increase due to the difficultly in growing the GaN compound semiconductor in a larger size area.
In order to address the above drawbacks, techniques for forming nano-scale LEDs have been researched wherein the thin film GaN LED is formed in a bar shape with a p-n junction using a GaN compound semiconductor, or zinc oxide. In the case of a LED formed by arranging a plurality of nano-rods, growth in a larger area is possible because the mismatch of the lattice constant or the thermal expansion coefficient difference of the LED is mitigated due to the structural characteristics of the nano-rods that are separated from each other. The nano-rod arrangement structure may have a substantially high light extraction efficiency because the nano-rod arrangement structure has a substantially low average refraction rate due to spaces between the nano-rods, and due to the structural characteristics that disperse light. In the case of a LED that includes nano-rods, it is difficult to supply a substantially uniform current to each of the nano-rods. Also, the method of growing the nano-rods may be inefficient.